Hypoxia-inducible factor-1alpha in hepatic fibrosis: A promising therapeutic target

UCHL1-dependent control of hypoxia-inducible factor transcriptional activity during liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in most types of chronic liver disease. At the cellular level, liver fibrosis is associated with the activation of hepatic stellate cells (HSCs) which transdifferentiate into a myofibroblast-like phenotype that is contractile, proliferative and profibrogenic. HSC transdifferentiation induces genome-wide changes in gene expression that enable the cell to adopt its profibrogenic functions. We have previously identified that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is highly induced following HSC activation; however, the cellular targets of its deubiquitinating activity are poorly defined. Here, we describe a role for UCHL1 in regulating the levels and activity of hypoxia-inducible factor 1 (HIF1), an oxygen-sensitive transcription factor, during HSC activation and liver fibrosis. HIF1 is elevated during HSC activation and promotes the expression of profibrotic mediator HIF target genes. Increased HIF1α expression correlated with induction of UCHL1 mRNA and protein with HSC activation. Genetic deletion or chemical inhibition of UCHL1 impaired HIF activity through reduction of HIF1α levels. Furthermore, our mechanistic studies have shown that UCHL1 elevates HIF activity through specific cleavage of degradative ubiquitin chains, elevates levels of pro-fibrotic gene expression and increases proliferation rates. As we also show that UCHL1 inhibition blunts fibrogenesis in a pre-clinical 3D human liver slice model of fibrosis, these results demonstrate how small molecule inhibitors of DUBs can exert therapeutic effects through modulation of HIF transcription factors in liver disease. Furthermore, inhibition of HIF activity using UCHL1 inhibitors may represent a therapeutic opportunity with other HIF-related pathologies.

Anlotinib Attenuates Liver Fibrosis by Regulating the Transforming Growth Factor β1/Smad3 Signaling Pathway

BACKGROUND

Hepatic stellate cell hyperactivation is a central link in liver fibrosis development, transforming growth factor β1 (TGF-β1) is a key activator of HSCs.

AIMS

This study investigated whether anlotinib attenuates CCl4 induced liver fibrosis in mice and explored its antifibrotic mechanism.

METHODS

We used the human hepatic stellate cell line LX-2 for in vitro assays and used TGF-β1 to induce hepatic fibrosis in LX-2 cells. We analyzed cytotoxicity using a cell-counting kit-8 and transwell chambers to detect the migratory ability of LX-2 cells. Western blotting was used to detect the protein levels of collagen type I, α-smooth muscle actin, and p-Smad3. In addition, mice with CCl4-induced hepatic fibrosis were used as in vivo models. Histopathological examination was performed using H&E staining, Masson's trichrome staining, and immunohistochemistry.

RESULTS

Anlotinib significantly reversed TGF-β1-induced protein levels of Col I, α-SMA and p-Smad3 and inhibits migratory and proliferative abilities in vitro using LX-2 cells. CCl4 cause F4 grade (Ishak) hepatic fibrosis, liver inflammatory scores ranged from 12 to 14 (Ishak), a mean ALT measurement of 130 U/L and a mean measurement AST value of 119 U/L in mice. However, the CCl4-induced changes were markedly attenuated by anlotinib treatment, which returned to F2 grade (Ishak) hepatic fibrosis, liver inflammatory scores ranged from 4 to 6 (Ishak), a mean ALT measurement of 40 U/L and a mean measurement AST value of 56 U/L in mice.

CONCLUSIONS

Our results suggest that anlotinib-mediated suppression of liver fibrosis is related to the inhibition of TGF-β1 signaling pathway. Hepatic stellate cell hyper activation is a central link in liver fibrosis development, transforming growth factor β1 is a key activator of HSCs. Anlotinib is a multi-targeted tyrosine kinase inhibitor that has similar targets to nintedanib, a clinically used anti-pulmonary fibrosis drug. Our study demonstrates an FDA-approved drug-anlotinib-that could prevent liver fibrosis and inflammation. Experiments in cell cultures and mice show that anlotinib can inhibit the activation of hepatic stellate cells by down-regulating the TGFβ1/smad3 pathway, thereby reversing liver fibrosis. In animal experiments, anlotinib showed protective effects on the CCl4-induced liver damage, including ameliorating liver inflammation, reversing liver fibrosis and reducing liver enzymes. This is a very good signal, anlotinib may be useful for halting or reversing the progression of liver fibrosis and could be employed in the development of novel therapeutic drugs for the management of chronic liver diseases.

Hepatoprotective Effect of Medicine Food Homology Flower Saffron against CCl4-Induced Liver Fibrosis in Mice via the Akt/HIF-1α/VEGF Signaling Pathway

Liver fibrosis refers to a complex inflammatory response caused by multiple factors, which is a known cause of liver cirrhosis and even liver cancer. As a valuable medicine food homology herb, saffron has been widely used in the world. Saffron is commonly used in liver-related diseases and has rich therapeutic and health benefits. The therapeutic effect is satisfactory, but its mechanism is still unclear. In order to clarify these problems, we planned to determine the pharmacological effects and mechanisms of saffron extract in preventing and treating liver fibrosis through network pharmacology analysis combined with in vivo validation experiments. Through UPLC-Q-Exactive-MS analysis, a total of fifty-six nutrients and active ingredients were identified, and nine of them were screened to predict their therapeutic targets for liver fibrosis. Then, network pharmacology analysis was applied to identify 321 targets for saffron extract to alleviate liver fibrosis. Functional and pathway enrichment analysis showed that the putative targets of saffron for the treatment of hepatic fibrosis are mainly involved in the calcium signaling pathway, the HIF-1 signaling pathway, endocrine resistance, the PI3K/Akt signaling pathway, lipid and atherosclerosis, and the cAMP signaling pathway. Based on the CCl4-induced liver fibrosis mice model, we experimentally confirmed that saffron extract can alleviate the severity and pathological changes during the progression of liver fibrosis. RT-PCR and Western blotting analysis confirmed that saffron treatment can prevent the CCl4-induced upregulation of HIF-1α, VEGFA, AKT, and PI3K, suggesting that saffron may regulate AKT/HIF-1α/VEGF and alleviate liver fibrosis.

FTY-720 alleviates diabetes-induced liver injury by inhibiting oxidative stress and inflammation

We aimed to investigate the protective effect of FTY-720 on liver injury and explore its potential mechanism in diabetic mice. The diabetic mouse model was induced with streptozotocin and FTY-720 was administered for 12 weeks. We assayed biocharacters and liver function and used histopathology staining to evaluate the protective effects of FTY-720 against diabetic liver injury. Levels of oxidative stress and inflammation in the liver were observed. mRNA and protein levels of essential enzymes for glucose metabolism were quantified in the liver and the protein expression of TLR4, HIF1α and NF-κB was determined. In vivo results revealed that FTY-720 significantly lowered blood glucose and lipids and improved liver function and alleviated liver fibrosis in diabetic mice. FTY-720 reduced oxidative stress and inflammation, with the increased catalase activity and reduced levels of malondialdehyde, myeloperoxidase, IL-1β, IL-6, TNF-α, TGF-β, and MCP1. Furthermore, FTY-720 modulated glucose metabolism in liver and elevated the ATP production, showing the promotion of glycogenesis and glycolysis and inhibition of gluconeogenesis. Moreover, FTY-720 inhibited the expression of TLR4 and HIF1α, contributing to restoration of liver function. In conclusion, FTY-720 ameliorates diabetes-induced liver injury and improves glucose homeostasis by inhibiting oxidative stress and inflammation and may be a promise drug for treatment of liver disease.

Mechanisms of main components in Curcuma longa L. on hepatic fibrosis based on network pharmacology and molecular docking: A review

BACKGROUND

Hepatic fibrosis is a great concern in public health. While effective drugs for its treatment are lacking, Curcuma longa L. (CL) has been reported as a promising therapeutic. We aimed to uncover the core components and mechanisms of CL against hepatic fibrosis via a network pharmacology approach.

METHODS

The main components of CL were obtained and screened. While targets of components and disease were respectively collected using SwissTargetPrediction and online databases, common targets were assessed. A protein-protein interaction (PPI) network was constructed, and core targets were identified. GO and KEGG pathway enrichment analyses were performed, and molecular docking was conducted to validate the binding of core components in CL on predicted core targets.

RESULTS

Nine main components from CL based on high-performance liquid chromatography (HPLC) and 63 anti-fibrosis targets were identified, and a PPI network and a component target-disease target network were constructed. Apigenin, quercetin, demethoxycurcumin, and curcumin are likely to become key phenolic-based components and curcuminoids for the treatment of hepatic fibrosis, respectively. KEGG pathway enrichment analysis revealed that the HIF-1 signaling pathway (hsa04066) was most significantly enriched. Considering core targets of the PPI network and a network of the common targets and pathways enriched, AKT1, MAPK1, EGFR, MTOR, and SRC may be the core potential targets of CL against hepatic fibrosis. Molecular docking was carried out to verify the binding of above core components to core targets.

CONCLUSIONS

The therapeutic effect of CL on hepatic fibrosis may be attributed to multi-components, multi-targets, and multi-pathways.

Inhibitory effect of miR-138-5p on choroidal fibrosis in lens-induced myopia guinea pigs via suppressing the HIF-1α signaling pathway

Myopia is one of the most common eye diseases in children and adolescents worldwide. Currently, there is no effective treatment in clinical practice. Ocular tissue fibrosis is involved in the development of myopia and this study aimed to investigate the effect of miR-138-5p on choroidal fibrosis in myopic guinea pigs via regulating the HIF-1α signaling pathway. First, guinea pigs were randomly divided into a normal control (NC) group, a lens-induced myopia (LIM) group, a LIM + miR-138-5p-carried Lentivirus treatment (LV) group, and a LIM + miR-138-5p-Vector treatment (VECTOR) group. All animals were induced experimental myopia with a -6.0 diopter lens except those in the NC group. Meanwhile, animals in the LV group were supplemented with 5 μl of miR-138-5p-carried Lentivirus, while those in the VECTOR group were only supplemented with the same volume of miR-138-5p-Vector. After myopia induction for 2 and 4 weeks, the refractive status and other ocular parameters of the guinea pigs were measured. Further, the expression of hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β, collagen I, hydroxyproline (HYP), interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and a-smooth muscle actin (α-SMA) in choroidal tissues was investigated. Results showed that the refraction and axial length of the experimental myopic guinea pigs increased, and choroid fibrosis aggravated after experimental myopic induction. miR-138-5p can efficiently decrease the refraction and ocular length, and ameliorate the choroidal fibrosis of the experimental myopic guinea pigs via downregulating the fibrosis-related TGF-β1, collagen I, HYP, IL-1β, TNF-α, and α-SMA expression through inhibiting the HIF-1α signaling pathway. Our results provide new insight into controlling myopic development using microRNAs in clinical practice.

Investigation of effective components and action mechanism of Yiguanjian in treatment of liver fibrosis based on network pharmacology

BACKGROUND

Traditional Chinese medicine compounds are characterized by the comprehensive adjustment of multiple components and show unique advantages in the prevention and treatment of liver fibrosis. Yiguanjian (YGJ) is a famous prescription for nourishing Yin to soothe the liver, which can improve the symptoms of liver fibrosis, and understanding its anti-liver fibrosis mechanism can promote its development and use.

AIM

To explore the mechanism of YGJ in the treatment of liver fibrosis through network pharmacology and to experi-mentally validate the initial results obtained.

METHODS

Components of YGJ and potentially targeted proteins were downloaded from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. The targets of liver fibrosis were accessed from GeneCard and OMIM databases. STRING database was utilized to construct a protein-protein interaction (PPI) network based on the components of YGJ and the targets of liver fibrosis. The PPI network was subjected to random walk with restart (RWR) to obtain key genes, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed based on the DAVID database. For animal experimental validation, eighteen SD rats were randomly assigned to a normal group, a model group, and a YGJ group. The rats in the model group and YGJ group were intraperitoneally injected with 50% CCl₄ olive oil solution for 6 wk to induce liver fibrosis, and rats in the normal group were intraperitoneally injected with the same amount of olive oil solution. Then, the rats of the YGJ group were given YGJ decoction (6.67 g/kg) daily for 4 weeks. Meanwhile, rats in the other groups were given distilled water. Blood and liver samples were collected, and the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum of rats were detected with an automated analyzer. Pathological changes in liver tissue were observed by hematoxylin-eosin (HE) and Masson staining. Western blot and qRT-PCR were used to detect the expression of key proteins and genes in the liver.

RESULTS

A total of 52 components and 186 potential targets of YGJ were obtained, and 1080 targets of liver fibrosis were screened. The top 10 genes with the high-affinity scores to the drug targets were STAT6, SRC, MAPK3, STX1A, EP300, STAT3, PLG, CTNNB1, CDKN1B, and CANX. The top 50 genes were mainly enriched in response to PI3K- Akt signaling pathway and FoxO signaling pathway, etc. In CCl4-induced liver fibrosis rats, YGJ decoction could significantly improve liver lesions and reduce fibrosis. YGJ decoction could reduce α-SMA expression, promote the expression of phosphorylated STAT6, increase the protein expression of PPAR-γ and CD163 and the mRNA expression of Arg-1, CD206, and CD163, and inhibit the gene expression of IL-6.

CONCLUSION

The therapeutic effect of YGJ decoction for liver fibrosis involves multiple components and multiple pathways, including the STAT6/PPAR-γ pathway.

Ganoderma lucidum: Current advancements of characteristic components and experimental progress in anti-liver fibrosis

Ganoderma lucidum (G. lucidum, Lingzhi) is a well-known herbal medicine with a variety of pharmacological effects. Studies have found that G. lucidum has pharmacological effects such as antioxidant, antitumor, anti-aging, anti-liver fibrosis, and immunomodulation. The main active components of G. lucidum include triterpenoids, polysaccharides, sterols, peptides and other bioactive components. Among them, the triterpenoids and polysaccharide components of G. lucidum have a wide range of anti-liver fibrotic effects. Currently, there have been more reviews and studies on the antioxidant, antitumor, and anti-aging properties of G. lucidum. Based on the current trend of increasing number of liver fibrosis patients in the world, we summarized the role of G.lucidum extract in anti-liver fibrosis and the effect of G. lucidum extract on liver fibrosis induced by different pathogenesis, which were discussed and analyzed. Research and development ideas and references are provided for the subsequent application of G. lucidum extracts in anti-liver fibrosis treatment.

Hypoxia-induced factor and its role in liver fibrosis

Liver fibrosis develops as a result of severe liver damage and is considered a major clinical concern throughout the world. Many factors are crucial for liver fibrosis progression. While advancements have been made to understand this disease, no effective pharmacological drug and treatment strategies have been established that can effectively prevent liver fibrosis or even could halt the fibrotic process. Most of those advances in curing liver fibrosis have been aimed towards mitigating the causes of fibrosis, including the development of potent antivirals to inhibit the hepatitis virus. It is not practicable for many individuals; however, a liver transplant becomes the only suitable alternative. A liver transplant is an expensive procedure. Thus, there is a significant need to identify potential targets of liver fibrosis and the development of such agents that can effectively treat or reverse liver fibrosis by targeting them. Researchers have identified hypoxia-inducible factors (HIFs) in the last 16 years as important transcription factors driving several facets of liver fibrosis, making them possible therapeutic targets. The latest knowledge on HIFs and their possible role in liver fibrosis, along with the cell-specific activities of such transcription factors that how they play role in liver fibrosis progression, is discussed in this review.

miR-345-5p curbs hepatic stellate cell activation and liver fibrosis progression by suppressing hypoxia-inducible factor-1alpha expression

Hepatic fibrosis, as a common stage of multiple liver diseases, currently has no effective drug treatment. Emerging evidence shows that miRNAs participate in the progression of liver fibrosis. However, the potential role of miRNAs in hepatic fibrosis is not yet fully understood. Herein, we first confirmed that miR-345-5p expression was significantly decreased in activated hepatic stellate cells (HSCs) and fibrotic livers. Functional analysis showed that overexpression of miR-345-5p in human LX-2 cells suppressed the expression of profibrotic markers and cellular proliferation in vitro. Using a dual-luciferase assay, we demonstrated that miR-345-5p regulates HSC activation by targeting the 3'UTR of HIF-1α mRNA. In addition, overexpression of miR-345-5p in vivo alleviated murine liver fibrosis induced by carbon tetrachloride (CCl4) injection, high-fat diet (HFD) feeding and bile duct ligation (BDL). Furthermore, overexpression of miR-345-5p downregulated the expression of HIF-1α and fibrosis markers in livers from different fibrosis models. Collectively, we conclude that miR-345-5p mediates the activation of HSCs by targeting HIF-1α, which subsequently modulates TGFβ/Smad2/Smad3 signaling. Thus, miR-345-5p may become a novel therapeutic target for the treatment of liver fibrosis.

Disulfiram inhibits liver fibrosis in rats by suppressing hepatic stellate cell activation and viability

Background

Liver fibrosis is a wound-healing response to chronic injury, featuring with excess accumulation of extracellular matrix secreted by the activated hepatic stellate cells (HSC). Disulfiram (DSF), also known as Antabuse, has been used for the treatment of alcohol addiction and substance abuse. Recently, overwhelming studies had revealed anti-cancer effects of DSF in multiple cancers, including liver cancer. But the actual effects of DSF on liver fibrosis and liver function remain unknown.

Methods

In this study, we evaluated the effects of low-dose DSF in CCl4- and Bile Duct Ligation (BDL)—induced hepatic fibrosis rat models. Cell proliferation was detected by using the Cell-Light™ EdU Apollo®567 Cell Tracking Kit. Cell apoptosis was analyzed using a TdT-mediated dUTP nick end labeling (TUNEL) kit, viability was measured with Cell Counting Kit-8(CCK8). Relative mRNA expression of pro-fibrogenic was assessed using quantitative RT-PCR. The degree of liver fibrosis, activated HSCs, were separately evaluated through Sirius Red-staining, immunohistochemistry and immunofluorescence. Serum alanine aminotransferase (ALT) and asparagine aminotransferase (AST) activities were detected with ALT and AST detecting kits using an automated analyzer.

Results

Liver fibrosis was distinctly attenuated while liver functions were moderately ameliorated in the DSF-treated group. Activation and proliferation of primary rat HSCs isolated from rat livers were significantly suppressed by low-dose DSF. DSF also inhibited the viability of in vitro cultured rat or human HSC cells dose-dependently but had no repressive role on human immortalized hepatocyte THLE-2 cells. Interestingly, upon DSF treatment, the viability of LX-2 cells co-cultured with THLE-2 was significantly inhibited, while that of THLE-2 co-cultured with LX-2 was increased. Further study indicated that HSCs apoptosis was increased in DSF/CCl4-treated liver samples. These data indicated that DSF has potent anti-fibrosis effects and protective effects toward hepatocytes and could possibly be repurposed as an anti-fibrosis drug in the clinic.

Conclusions

DSF attenuated ECM remodeling through suppressing the transformation of quiet HSCs into proliferative, fibrogenic myofibroblasts in hepatic fibrosis rat models. DSF provides a novel approach for the treatment of liver fibrosis.

HIF-1α in Osteoarthritis: From Pathogenesis to Therapeutic Implications

Osteoarthritis is a common age-related joint degenerative disease. Pain, swelling, brief morning stiffness, and functional limitations are its main characteristics. There are still no well-established strategies to cure osteoarthritis. Therefore, better clarification of mechanisms associated with the onset and progression of osteoarthritis is critical to provide a theoretical basis for the establishment of novel preventive and therapeutic strategies. Chondrocytes exist in a hypoxic environment, and HIF-1α plays a vital role in regulating hypoxic response. HIF-1α responds to cellular oxygenation decreases in tissue regulating survival and growth arrest of chondrocytes. The activation of HIF-1α could regulate autophagy and apoptosis of chondrocytes, decrease inflammatory cytokine synthesis, and regulate the chondrocyte extracellular matrix environment. Moreover, it could maintain the chondrogenic phenotype that regulates glycolysis and the mitochondrial function of osteoarthritis, resulting in a denser collagen matrix that delays cartilage degradation. Thus, HIF-1α is likely to be a crucial therapeutic target for osteoarthritis via regulating chondrocyte inflammation and metabolism. In this review, we summarize the mechanism of hypoxia in the pathogenic mechanisms of osteoarthritis, and focus on a series of therapeutic treatments targeting HIF-1α for osteoarthritis. Further clarification of the regulatory mechanisms of HIF-1α in osteoarthritis may provide more useful clues to developing novel osteoarthritis treatment strategies.

OTUD7B (Cezanne) ameliorates fibrosis after myocardial infarction via FAK-ERK/P38 MAPK signaling pathway

Fibrosis is one of the crucial reasons for cardiac dysfunction after myocardial infarction (MI). Understanding the underlying molecular mechanism that causes fibrosis is crucial to developing effective therapy. Recently, OUT domain-containing 7B (OTUD7B), also called Cezanne, a multifunctional deubiquitylate, has been found to play various roles in cancer and vascular diseases and control many important signaling pathways, including inflammation, proliferation, and so on. However, whether OTUD7B plays a role in fibrosis caused by MI remains unclear. Our study aimed to explore the function of OTUD7B in cardiac fibrosis and investigate the underlying mechanism. We found that the expression of OTUD7B was downregulated in the MI rat model and cultured cardiac fibroblasts (CFs) in hypoxic conditions and after TGF-β1 treatment. In vitro, silencing OTUD7B using small interfering RNA (siRNA) increased α-SMA (smooth muscle actin α) and collagen Ⅰ levels in CFs, whereas the overexpression of OTUD7B using adenovirus decreased their expression. Mechanistically, OTUD7B could regulate the phosphorylation of focal adhesion kinase (FAK), a non-receptor tyrosine kinase that has been proved to act as a potential mediator of fibrosis, and ERK/P38 MAPK was involved in this regulation process. In vitro, overexpression of OTUD7B downregulated the phosphorylation level of FAK and then inhibited ERK/P38 phosphorylation, thus leading to decreased α-SMA and collagen Ⅰ expressions, while OTUD7B knockdown showed an opposite result. These findings suggest that OTUD7B could become a potentially effective therapeutic strategy against fibrosis after MI.

Targeting SYK of monocyte-derived macrophages regulates liver fibrosis via crosstalking with Erk/Hif1α and remodeling liver inflammatory environment

Liver fibrosis is a danger signal indicating a huge risk of liver cancer occurrence, but there is still no effective clinical means to regulate the progress of liver fibrosis. Although a variety of drugs targeting SYK have been developed for tumors and autoimmune diseases, the mechanism and specific efficacy of SYK's role in liver fibrosis are not yet clear. Our studies based on chronic CCL4, bile duct ligation, and subacute TAA mouse models show that SYK in monocyte-derived macrophages (MoMFs) is fully dependent on phosphorylation of Erk to up-regulate the expression of Hif1α, thereby forming the crosstalk with SYK to drive liver fibrosis progress. We have evaluated the ability of the small molecule SYK inhibitor GS9973 in a variety of models. Contrary to previous impressions, high-frequency administration of GS9973 will aggravate CCL4-induced liver fibrosis, which is especially unsuitable for patients with cholestasis whose clinical features are bile duct obstruction. In addition, we found that inhibition of MoMFs SYK impairs the expression of CXCL1, on one hand, it reduces the recruitment of CD11bhiLy6Chi inflammatory cells, and on the other hand, it promotes the phenotype cross-dress process of pro-resolution MoMFs, thereby remodeling the chronic inflammatory environment of the fibrotic liver. Our further findings indicate that on the basis of the administration of CCR2/CCR5 dual inhibitor Cenicriviroc, further inhibiting MoMFs SYK may give patients with fibrosis additional benefits.

Lipid Metabolism Disorders in the Comorbid Course of Nonalcoholic Fatty Liver Disease and Chronic Obstructive Pulmonary Disease

Non-alcoholic fatty liver disease (NAFLD) is currently among the most common liver diseases. Unfavorable data on the epidemiology of metabolic syndrome and obesity have increased the attention of clinicians and researchers to the problem of NAFLD. The research results allow us to emphasize the systemicity and multifactoriality of the pathogenesis of liver parenchyma lesion. At the same time, many aspects of its classification, etiology, and pathogenesis remain controversial. Local and systemic metabolic disorders are also a part of the pathogenesis of chronic obstructive pulmonary disease and can influence its course. The present article analyzes the metabolic pathways mediating the links of impaired lipid metabolism in NAFLD and chronic obstructive pulmonary disease (COPD). Free fatty acids, cholesterol, and ceramides are involved in key metabolic and inflammatory pathways underlying the pathogenesis of both diseases. Moreover, inflammation and lipid metabolism demonstrate close links in the comorbid course of NAFLD and COPD.

Hypoxia Inducible Factor 1A Supports a Pro-Fibrotic Phenotype Loop in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. The IPF-conditioned matrix (IPF-CM) system enables the study of matrix–fibroblast interplay. While effective at slowing fibrosis, nintedanib has limitations and the mechanism is not fully elucidated. In the current work, we explored the underlying signaling pathways and characterized nintedanib involvement in the IPF-CM fibrotic process. Results were validated using IPF patient samples and bleomycin-treated animals with/without oral and inhaled nintedanib. IPF-derived primary human lung fibroblasts (HLFs) were cultured on Matrigel and then cleared using NH₄OH, creating the IPF-CM. Normal HLF-CM served as control. RNA-sequencing, PCR and western-blots were performed. HIF1α targets were evaluated by immunohistochemistry in bleomycin-treated rats with/without nintedanib and in patient samples with IPF. HLFs cultured on IPF-CM showed over-expression of ‘HIF1α signaling pathway’ (KEGG, p < 0.0001), with emphasis on SERPINE1 (PAI-1), VEGFA and TIMP1. IPF patient samples showed high HIF1α staining, especially in established fibrous tissue. PAI-1 was overexpressed, mainly in alveolar macrophages. Nintedanib completely reduced HIF1α upregulation in the IPF-CM and rat-bleomycin models. IPF-HLFs alter the extracellular matrix, thus creating a matrix that further propagates an IPF-like phenotype in normal HLFs. This pro-fibrotic loop includes the HIF1α pathway, which can be blocked by nintedanib.

Apigenin suppresses TGF-β1-induced cardiac fibroblast differentiation and collagen synthesis through the downregulation of HIF-1α expression by miR-122-5p

BACKGROUND

Apigenin can reduce cardiomyocyte hypertrophy by downregulating hypoxia inducible factor-1 alpha (HIF-1α) expression. However, its effects on cardiac fibroblasts (CFs) and its exact inhibitory molecular mechanisms on HIF-1α remain unclear.

PURPOSE

This study aims to examine the effects of apigenin on cell proliferation and differentiation, microRNA-122-5p (miR-122-5p) expression, and HIF-1α-mediated Smad signaling pathway in transforming growth factor beta 1 (TGF-β1)-stimulated CFs and cardiac fibrosis and to investigate the relationship between miR-122-5p and HIF-1α.

METHODS

The TGF-β1-stimulated CFs, the combination of TGF-β1-stimulated and miR-122-5p mimic-transfected CFs, the combination of TGF-β1-stimulated and miR-122-5p inhibitor-transfected CFs, and the isoproterenol-induced cardiac fibrotic mice were used and treated with or without apigenin. The recombinant lentiviruses overexpressing HIF-1α vector and miR-122-5p mimic were co-transfected to observe their interaction. Related mRNA and protein expressions and myocardial collagen were determined. The luciferase reporter gene that contains HIF-1α wild type or mutant type 3'-UTR was used, and the luciferase activity was determined to verify the direct link between miR-122-5p and HIF-1α.

RESULTS

In the TGF-β1-stimulated CFs, apigenin treatment increased the miR-122-5p and Smad7 expressions and decreased the HIF-1α, α-smooth muscle actin, collagen Ⅰ/Ⅲ, Smad2/3, and p-Smad2/3 expressions. Similar and inverse results were observed in the miR-122-5p mimic- and inhibitor-transfected CFs, respectively. Moreover, the miR-122-5p mimic could antagonize the effects of TGF-β1 in the TGF-β1 and miR-122-5p mimic-combined CFs, and the miR-122-5p inhibitor could enhance the effects of TGF-β1 in the TGF-β1 and miR-122-5p inhibitor-combined CFs. In the two aforementioned cell models, the addition of apigenin could further enhance the effects of miR-122-5p mimic and partially reverse the effects of miR-122-5p inhibitor. After treatment of HIF-1α-transfected CFs with miR-122-5p mimic, the HIF-1α expression decreased. Further study confirmed that HIF-1α was a direct target of miR-122-5p. Apigenin also decreased the myocardial collagen accumulation in cardiac fibrotic mice.

CONCLUSION

Apigenin could suppress the differentiation and collagen synthesis of TGF-β1-stimulated CFs and mouse cardiac fibrosis, and its mechanisms were related to the increment of miR-122-5p expression and subsequent downregulation of HIF-1α expression via direct interaction, which might finally result in the decrements of Smad2/3 and p-Smad2/3 expressions and increment of Smad7 expression.

Cholesterol Induces Nrf-2- and HIF-1α-Dependent Hepatocyte Proliferation and Liver Regeneration to Ameliorate Bile Acid Toxicity in Mouse Models of NASH and Fibrosis

Nonalcoholic steatohepatitis (NASH) is currently one of the most common liver diseases worldwide. The toxic effects of lipids and bile acids contribute to NASH. The regenerative pathway in response to damage to the liver includes activation of the inflammatory process and priming of hepatocytes to proliferate to restore tissue homeostasis. However, the effects of cholesterol on bile acid toxicity, inflammation, and fibrosis remain unknown. We have used two mouse models of bile acid toxicity to induce liver inflammation and fibrosis. A three-week study was conducted using wild-type mice receiving an atherogenic diet (1% (w/w) cholesterol and 0.5% (w/w) cholic acid) and its separate constituents. Mdr2-/- mice were fed a high-cholesterol-enriched diet or standard AIN-93 diet for 6 weeks. We measured serum transaminase levels to assess liver tissue necrosis and fibrosis; iNOS, SAA1, SAA2, and F4/80 levels to determine liver inflammation; PCNA and HGF levels to evaluate proliferative response; and Nrf-2, HIF-1α, and downstream gene expression to establish protective responses. In both studies, high bile acid levels increased serum transaminases and liver fibrosis, whereas cholesterol supplementation attenuated these effects. Cholesterol supplementation activated survival and the robustness of HIF-1α and Nrf-2 gene expression in hepatocytes, induced liver inflammation and hepatocyte proliferation, and inhibited stellate cell hyperplasia and fibrosis. In conclusion, our data show for the first time that cholesterol intake protects against bile acid liver toxicity. The balance between hepatic cholesterol and bile acid levels may be of prognostic value in liver disease progression and trajectory.

Activation of TWIST Transcription by Chromatin Remodeling Protein BRG1 Contributes to Liver Fibrosis in Mice

Liver fibrosis is a complex pathophysiological process to which many different cell types contribute. Endothelial cells play versatile roles in the regulation of liver fibrosis. The underlying epigenetic mechanism is not fully appreciated. In the present study, we investigated the role of BRG1, a chromatin remodeling protein, in the modulation of endothelial cells in response to pro-fibrogenic stimuli in vitro and liver fibrosis in mice. We report that depletion of BRG1 by siRNA abrogated TGF-β or hypoxia induced down-regulation of endothelial marker genes and up-regulation of mesenchymal marker genes in cultured endothelial cells. Importantly, endothelial-specific BRG1 deletion attenuated CCl₄ induced liver fibrosis in mice. BRG1 knockdown in vitro or BRG1 knockout in vivo was accompanied by the down-regulation of TWIST, a key regulator of endothelial phenotype. Mechanistically, BRG1 interacted with and was recruited to the TWIST promoter by HIF-1α to activate TWIST transcription. BRG1 silencing rendered a more repressive chromatin structure surrounding the TWIST promoter likely contributing to TWIST down-regulation. Inhibition of HIF-1α activity dampened liver fibrosis in mice. Similarly, pharmaceutical inhibition of TWIST alleviated liver fibrosis in mice. In conclusion, our data suggest that epigenetic activation of TWIST by BRG1 contributes to the modulation of endothelial phenotype and liver fibrosis. Therefore, targeting the HIF1α-BRG1-TWIST axis may yield novel therapeutic solutions to treat liver fibrosis.

Hypoxia induces the activation of hepatic stellate cells through the PVT1-miR-152-ATG14 signaling pathway

Increasing studies have indicated that hypoxia serves as a pivotal microenvironmental factor that facilitates activation of hepatic stellate cells (HSCs). However, the mechanism by which hypoxia activates HSCs is not clear. Here, we demonstrated that plasmacytoma variant translocation 1 (PVT1) and autophagy were overexpressed in liver fibrotic specimens. In primary mouse HSCs, both PVT1 and autophagy were induced by hypoxia. Further study showed that hypoxia-induced autophagy depended on expression of PVT1 and miR-152 in HSCs. Luciferase reporter assay indicated that autophagy-related gene 14 (ATG14) was a direct target of miR-152. In addition, inhibition of autophagy by 3-methyladenine and Beclin-1 siRNA impeded activation of HSCs cultured in 1% O₂. Taken together, autophagy induction via the PVT1-miR-152-ATG14 signaling pathway contributes to activation of HSCs under hypoxia condition.

Research progress on the anti-hepatic fibrosis action and mechanism of natural products

Hepatic fibrosis is the most common pathological feature of most chronic liver diseases, and its continuous deterioration gradually develops into liver cirrhosis and eventually leads to liver cancer. At present, there are many kinds of drugs used to treat liver fibrosis. However, Western drugs tend to only target single genes/proteins and induce many adverse reactions. Most of the mechanisms and active ingredients of traditional Chinese medicine (TCM) are not clear, and there is a lack of unified diagnosis and treatment standards. Natural products, which are characterized by structural diversity, low toxicity, and origination from a wide range of sources, have unique advantages and great potential in anti-liver fibrosis. This article summarizes the work done over the previous decade, on the active ingredients in natural products that are reported to have anti-hepatic fibrosis effects. The effective anti-hepatic fibrosis ingredients identified can be generally divided into flavonoids, saponins, polysaccharides and alkaloids. Mechanisms of anti-liver fibrosis include inhibition of liver inflammation, anti-lipid peroxidation injury, inhibition of the activation and proliferation of hepatic stellate cells (HSCs), modulation of the synthesis and secretion of pro-fibrosis factors, and regulation of the synthesis and degradation of the extracellular matrix (ECM). This review provides suggestions for the development of anti-hepatic fibrosis drugs.

PKM2 is the target of proanthocyanidin B2 during the inhibition of hepatocellular carcinoma

BACKGROUND

The treatment for advanced primary hepatocellular carcinoma (HCC) is sorafenib (SORA), while HCC has become increasingly drug resistant with enhanced aerobic glycolysis. The present study aimed to examine the chemotherapeutic effects of a flavonoid proanthocyanidin B2 (PB2) on HCC.

METHODS

Five kinds of HCC cell lines and LO2 were used to test the effect of PB2 on aerobic glycolysis. The proliferation, cell cycle, apoptosis and a xenograft mouse model were analyzed. Lentivirus overexpressed pyruvate kinase M2 (PKM2) or sh-PKM2 was used to verify the target of PB2. The detailed mechanism was investigated by immunofluorescence, co-immunoprecipitation, and western blotting.

RESULTS

PB2 inhibited the proliferation, induced cell cycle arrest, and triggered apoptosis of HCC cells in vivo and in vitro. PB2 also suppressed glucose uptake and lactate levels via the direct inhibition of the key glycolytic enzyme, PKM2. In addition, PKM2 inhibited the nuclear translocation of PKM2 and co-localization of PKM2/HIF-1α in the nucleus, leading to the inhibition of aerobic glycolysis. Co-treatment with PB2 was also effective in enhancing the chemosensitivity of SORA.

CONCLUSIONS

PB2 inhibited the expression and nuclear translocation of PKM2, therefore disrupting the interaction between PKM2/HSP90/HIF-1α, to suppress aerobic glycolysis and proliferation, and trigger apoptosis in HCC via HIF-1α-mediated transcription suppression.

Fluorofenidone affects hepatic stellate cell activation in hepatic fibrosis by targeting the TGF-β1/Smad and MAPK signaling pathways

The aim of the present research was to study the therapeutic impacts of fluorofenidone (AKF-PD) on pig serum (PS)-induced liver fibrosis in rats and the complex molecular mechanisms of its effects on hepatic stellate cells (HSCs). Wistar rats were randomly divided into normal control, PS and PS/AKF-PD treatment groups. The activated human HSC LX-2 cell line was also treated with AKF-PD. The expression of collagen I and III, and α-smooth muscle actin (α-SMA) was determined by immunohistochemical staining and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Western blotting and/or RT-qPCR analyses were used to determine the expression of transforming growth factor (TGF)-β1, α-SMA, collagen I, mothers against decapentaplegic homolog (Smad)-3, extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK). AKF-PD attenuated the degree of hepatic fibrosis and liver injury in vivo, which was associated with the downregulation of collagen I and III, and α-SMA at the mRNA and protein levels. In vitro, AKF-PD treatment significantly reduced the TGF-β1-induced activation of HSCs, as determined by the reduction in collagen I and α-SMA protein expression. The TGF-β1-induced upregulation of the phosphorylation of Smad 3, ERK1/2, p38 and JNK was attenuated by AKF-PD treatment. These findings suggested that AKF-PD attenuated the progression of hepatic fibrosis by suppressing HSCs activation via the TGF-β1/Smad and MAPK signaling pathways, and therefore that AKF-PD may be suitable for use as a novel therapeutic agent against liver fibrosis.

Integrated network analysis of transcriptomic and protein-protein interaction data in taurine-treated hepatic stellate cells

BACKGROUND

Studies show that the antifibrotic mechanism of taurine may involve its inhibition of the activation and proliferation of hepatic stellate cells (HSCs). Since the molecular mechanism of taurine-mediated antifibrotic activity has not been fully unveiled and is little studied, it is imperative to use “omics” methods to systematically investigate the molecular mechanism by which taurine inhibits liver fibrosis.

AIM

To establish a network including transcriptomic and protein-protein interaction data to elucidate the molecular mechanism of taurine-induced HSC apoptosis.

METHODS

We used microarrays, bioinformatics, protein-protein interaction (PPI) network, and sub-modules to investigate taurine-induced changes in gene expression in human HSCs (LX-2). Subsequently, all of the differentially expressed genes (DEGs) were subjected to gene ontology function and Kyoto encyclopedia of genes and genomes pathway enrichment analysis. Furthermore, the interactions of DEGs were explored in a human PPI network, and sub-modules of the DEGs interaction network were analyzed using Cytoscape software.

RESULTS

A total of 635 DEGs were identified in taurine-treated HSCs when compared with the controls. Of these, 304 genes were statistically significantly up-regulated, and 331 down-regulated. Most of these DEGs were mainly located on the membrane and extracellular region, and are involved in the biological processes of signal transduction, cell proliferation, positive regulation of extracellular regulated protein kinases 1 (ERK1) and ERK2 cascade, extrinsic apoptotic signaling pathway and so on. Fifteen significantly enriched pathways with DEGs were identified, including mitogen-activated protein kinase (MAPK) signaling pathway, peroxisome proliferators-activated receptor signaling pathway, estrogen signaling pathway, Th1 and Th2 cell differentiation, cyclic adenosine monophosphate signaling pathway and so on. By integrating the transcriptomics and human PPI data, nine critical genes, including MMP2, MMP9, MMP21, TIMP3, KLF10, CX3CR1, TGFB1, VEGFB, and EGF, were identified in the PPI network analysis.

CONCLUSION

Taurine promotes the apoptosis of HSCs via up-regulating TGFB1 and then activating the p38 MAPK-JNK-Caspase9/8/3 pathway. These findings enhance the understanding of the molecular mechanism of taurine-induced HSC apoptosis and provide references for liver disorder therapy.

Neotuberostemonine inhibits the differentiation of lung fibroblasts into myofibroblasts in mice by regulating HIF-1α signaling

Pulmonary fibrosis may be partially the result of deregulated tissue repair in response to chronic hypoxia. In this study we explored the effects of hypoxia on lung fibroblasts and the effects of neotuberostemonine (NTS), a natural alkaloid isolated from Stemona tuberosa, on activation of fibroblasts in vitro and in vivo. PLFs (primary mouse lung fibroblasts) were activated and differentiated after exposure to 1% O2 or treatment with CoCl2 (100 μmol/L), evidenced by markedly increased protein or mRNA expression of HIF-1α, TGF-β, FGF2, α-SMA and Col-1α/3α, which was blocked after silencing HIF-1α, suggesting that the activation of fibroblasts was HIF-1α-dependent. NTS (0.1-10 μmol/L) dose-dependently suppressed hypoxia-induced activation and differentiation of PLFs, whereas the inhibitory effect of NTS was abolished by co-treatment with MG132, a proteasome inhibitor. Since prolyl hydroxylation is a critical step in initiation of HIF-1α degradation, we further showed that NTS treatment reversed hypoxia- or CoCl2-induced reduction in expression of prolyl hydroxylated-HIF-1α. With hypoxyprobe immunofiuorescence staining, we showed that NTS treatment directly reversed the lower oxygen tension in hypoxia-exposed PLFs. In a mouse model of lung fibrosis, oral administration of NTS (30 mg·kg-1·d-1, for 1 or 2 weeks) effectively attenuated bleomycin-induced pulmonary fibrosis by inhibiting the levels of HIF-1α and its downstream profibrotic factors (TGF-β, FGF2 and α-SMA). Taken together, these results demonstrate that NTS inhibits the protein expression of HIF-1α and its downstream factors TGF-β, FGF2 and α-SMA both in hypoxia-exposed fibroblasts and in lung tissues of BLM-treated mice. NTS with anti-HIF-1α activity may be a promising pharmacological agent for the treatment of pulmonary fibrosis.

Hypoxia‑inducible factor 1α and ROCK1 regulate proliferation and collagen synthesis in hepatic stellate cells under hypoxia

Hypoxia serves a critical role in the pathogenesis of liver fibrosis. Hypoxia‑inducible factor 1α (HIF1‑α) is induced when cells are exposed to low O2 concentrations. Recently, it has been suggested that Rho‑associated coiled‑coil‑forming kinase 1 (ROCK1) may be an important HIF1‑α regulator. In the present study, it was analyzed whether crosstalk between HIF1‑α and ROCK1 regulates cell proliferation and collagen synthesis in hepatic stellate cells (HSCs) under hypoxic conditions. For this purpose, a rat hepatic HSC line (HSC‑T6) was cultured under hypoxic or normoxic conditions, and HIF1‑α and ROCK1 expression was measured at different time points. Additionally, HSC‑T6 cells were transfected with HIF1‑α small interfering RNA (siHIF1‑α), and measured protein expression and mRNA transcript levels of α‑smooth muscle actin, collagen 1A1 and ROCK1. Collagen 3A1 secretion was also measured by ELISA. Cell proliferation was assessed by the MTT assay under these hypoxic conditions. The results indicated that a specific ROCK inhibitor, Y‑27632, increased HIF1‑α and ROCK1 expression over time in HSC‑T6 cells in response to hypoxia. In addition, knockdown of HIF1‑α inhibited HSC‑T6 proliferation, suppressed collagen 1A1 expression, decreased collagen 3A1 secretion and attenuated ROCK1 expression. Notably, ROCK1 inhibition caused HSC‑T6 quiescence, suppressed collagen secretion and downregulated HIF1‑α expression. Collectively, these findings indicated that the interplay between HIF1‑α and ROCK1 may be a critical factor that regulates cell proliferation and collagen synthesis in rat HSCs under hypoxia.

p300/CBP as a Key Nutritional Sensor for Hepatic Energy Homeostasis and Liver Fibrosis

The overwhelming frequency of metabolic diseases such as obesity and diabetes are closely related to liver diseases, which might share common pathogenic signaling processes. These metabolic disorders in the presence of inflammatory response seem to be triggered by and to reside in the liver, which is the central metabolic organ that plays primary roles in regulating lipid and glucose homeostasis upon alterations of metabolic conditions. Recently, abundant emerging researches suggested that p300 and CREB binding protein (CBP) are crucial regulators of energy homeostasis and liver fibrosis through both their acetyltransferase activities and transcriptional coactivators. Plenty of recent findings demonstrated the potential roles of p300/CBP in mammalian metabolic homeostasis in response to nutrients. This review is focused on the different targets and functions of p300/CBP in physiological and pathological processes, including lipogenesis, lipid export, gluconeogenesis, and liver fibrosis, also provided some nutrients as the regulator of p300/CBP for nutritional therapeutic approaches to treat liver diseases.

PPARγ Antagonizes Hypoxia-Induced Activation of Hepatic Stellate Cell through Cross Mediating PI3K/AKT and cGMP/PKG Signaling

Background and Aims

Accumulating evidence reveals that PPARγ plays a unique role in the regulation of hepatic fibrosis and hepatic stellate cells (HSCs) activation. This study was aimed at investigating the role of PPARγ in hypoxia-induced hepatic fibrogenesis and its possible mechanism.

Methods

Rats used for CCl4-induced hepatic fibrosis model were exposed to hypoxia for 8 hours each day. Rats exposed to hypoxia were treated with or without the PPARγ agonist rosiglitazone. Liver sections were stained with HE and Sirius red staining 8 weeks later. HSCs were exposed to hypoxic environment in the presence or absence of rosiglitazone, and expression of PPARγ and two fibrosis markers, α-SMA and desmin, were measured using western blot and immunofluorescence staining. Next, levels of PPARγ, α-SMA, and desmin as well as PKG and cGMP activity were detected using PI3K/AKT and a cGMP activator or inhibitor.

Results

Hypoxia promoted the induction and progress of hepatic fibrosis and HSCs activation. Meanwhile, rosiglitazone significantly antagonized the effects induced by hypoxia. Signaling by sGC/cGMP/PKG promoted the inhibitory effect of PPARγ on hypoxia-induced activation of HSCs. Moreover, PI3K/AKT signaling or PDE5 blocked the above response of PPARγ.

Conclusion

sGC/cGMP/PKG and PI3K/AKT signals act on PPARγ synergistically to attenuate hypoxia-induced HSC activation.

The role of TRPV4 in fibrosis

The transient receptor potential vanilloid 4 (TRPV4) is a highly Ca²⁺-permeable non-selective cation channel in TRPV family. Accumulating evidence hints that TRPV4 play a significant role in a wide diversity of pathologic changes. Fibrosis is a kind of chronic disease which was characterized by the formation of excessive accumulation of extracellular matrix (ECM) components in tissues and organs. In recent years, a growing body of studies showed that TRPV4 acted as a crucial regulator in the progression of fibrosis including myocardial fibrosis, cystic fibrosis, pulmonary fibrosis, hepatic fibrosis and pancreatic fibrosis, suggesting TRPV4 may be a potential therapeutic vehicle in fibrotic diseases. However, the mechanisms by which TRPV4 regulates fibrosis are still undefined. In this review, firstly, we intend to sum up the collective knowledge of TRPV4. Then we provided the latent mechanism between TRPV4 and fibrosis. We also elaborated the distinct signaling pathways focus on TRPV4 with fibrosis. Finally, we discussed its potential as a novel therapeutic target for fibrosis.

Microarray analysis of differentially expressed genes in L929 mouse fibroblast cells exposed to leptin and hypoxia

Leptin and hypoxia are pro-fibrotic factors involved in fibrogenesis, however, the gene expression profiles remain to be fully elucidated. The aim of the present study was to investigate the regulatory roles of leptin and hypoxia on the L929 mouse fibroblast cell line. The cells were assigned to a normoxia, normoxia with leptin, hypoxia, and hypoxia with leptin group. The cDNA expression was detected using an Agilent mRNA array platform. The differentially expressed genes (DEGs) in response to leptin and hypoxia were identified using reverse transcription-quantitative polymerase chain reaction analysis, followed by clustering analysis, Gene Ontology analysis and pathway analysis. As a result, 54, 1,507 and 1,502 DEGs were found in response to leptin, hypoxia and the two combined, respectively, among which 52 (96.30%), 467 (30.99%) and 495 (32.96%) of the DEGs were downregulated. The most significant functional terms in response to leptin were meiosis I for biological process (P=0.0041) and synaptonemal complex for cell component (P=0.0013). Only one significant pathway responded to leptin, which was axon guidance (P=0.029). Flow cytometry confirmed that leptin promoted L929 cell proliferation. The most significant functional terms in response to hypoxia were ion binding for molecular function (P=7.8621E-05), glucose metabolic process for biological process (P=0.0008) and cell projection part for cell component (P=0.003). There were 12 pathways, which significantly responded to hypoxia (P<0.05) and the pathway with the highest significance was the chemokine signaling pathway (P=0.0001), which comprised 28 genes, including C-C motif ligand (CCL)1, C-X-C motif ligand (CXCL)9, CXCL10, son of sevenless homolog 1, AKT serine/threonine kinase 2, Rho-associated protein kinase 1, vav guanine nucleotide exchange factor 1, CCL17, arrestin β1 and C-C motif chemokine receptor 2. In conclusion, the present study showed that leptin and hypoxia altered the profiles of gene expression in L929 cells. These findings not only extend the cell spectrum of leptin on cell proliferation, but also improve current understanding of hypoxia in fibroblast cells.

Canonical hedgehog signalling regulates hepatic stellate cell-mediated angiogenesis in liver fibrosis

BACKGROUND AND PURPOSE

Hepatic stellate cells (HSCs) are liver-specific pericytes regulating angiogenesis during liver fibrosis. We aimed to elucidate the mechanisms by which hedgehog signalling regulated HSC angiogenic properties and to validate the therapeutic implications.

EXPERIMENTAL APPROACH

Rats and mice were treated with carbon tetrachloride for in vivo evaluation of hepatic angiogenesis and fibrotic injury. Diversified molecular approaches including real-time PCR, Western blot, luciferase reporter assay, chromatin immunoprecipitation, electrophoretic mobility shift assay and co-immunoprecipitation were used to investigate the underlying mechanisms in vitro.

KEY RESULTS

Angiogenesis was concomitant with up-regulation of Smoothened (SMO) and hypoxia inducible factor-1α (HIF-1α) in rat fibrotic liver. The SMO inhibitor cyclopamine and Gli1 inhibitor GANT-58 reduced expression of VEGF and angiopoietin 1 in HSCs and suppressed HSC tubulogenesis capacity. HIF-1α inhibitor PX-478 suppressed HSC angiogenic behaviour, and inhibition of hedgehog decreased HIF-1α expression. Furthermore, heat shock protein 90 (HSP90) was characterized as a direct target gene of canonical hedgehog signalling in HSCs. HSP90 inhibitor 17-AAG reduced HSP90 binding to HIF-1α, down-regulated HIF-1α protein abundance and decreased HIF-1α binding to DNA. 17-AAG also abolished 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) (a SMO agonist)-enhanced HSC angiogenic properties. Finally, the natural compound ligustrazine was found to inhibit canonical hedgehog signalling leading to suppressed angiogenic properties of HSCs in vitro and ameliorated liver fibrosis and sinusoidal angiogenesis in mice.

CONCLUSION AND IMPLICATIONS

We have provided evidence that the canonical hedgehog pathway controlled HSC-mediated liver angiogenesis. Selective inhibition of HSC hedgehog signalling could be a promising therapeutic approach for hepatic fibrosis.

Hypoxia drives the transition of human dermal fibroblasts to a myofibroblast-like phenotype via the TGF-β1/Smad3 pathway

Keloids, partially considered as benign tumors, are characterized by the overgrowth of fibrosis beyond the boundaries of the wound and are regulated mainly by transforming growth factor (TGF)-β1, which induces the transition of fibroblasts to myofibroblasts. Hypoxia is an important driving force in the development of lung and liver fibrosis by activating hypoxia inducible factor-1α and stimulating epithelial-mesenchymal transition. However, it is unknown whether and hypoxia can influence human dermal scarring. The aim of this study was to investigate whether hypoxia drives the transition of dermal fibroblasts to myofibroblasts and to clarify the potential transduction mechanisms involved. First, we observed that keloids are a relatively hypoxic tissue. Second, we found that hypoxia drives the transition of normal dermal fibroblasts to a myofibroblast-like phenotype [high expression of α-smooth muscle actin (α-SMA) and collagen I and III]. Finally, hypoxia effectively facilitated the nuclear import of the Smad2 and Smad3 complex, while blockade with the Smad3 inhibitor, SIS3, significantly impaired the expression of hypoxia-induced fibrosis-related molecules. Taken together, to the best of our knowledge, this study demonstrates for the first time that hypoxia facilitates the transition of dermal fibroblasts to myofibroblasts through the activation of the TGF-β1/Smad3 signaling pathway and our findings may provide a potential target for the treatment of keloids.

Limited mouth opening in oral submucous fibrosis: reasons, ramifications, and remedies

Limited mouth opening (LMO) in oral submucous fibrosis (OSF) has been attributed to both the submucosal and muscle fibrosis (MF). While reflectory trismus was proposed before as an auxiliary mechanism by another group, the stretch-mediated muscle damage (MSD), histopathological changes in blood vessels (such as endothelial dysfunction, endothelial hypertrophy, and endarteritis obliterans), and upregulated anaerobic isoforms of lactate dehydrogenase (LDH) have been proposed by us as complementary events leading to MF. Additionally, the amount of hypoxia-mediated upregulation of anaerobic isoforms of LDH determines the extent of MF. Radiotherapy (RT)-mediated release of reactive oxygen species causes vascular damage thereby worsening hypoxia. While the alteration in LDH levels secondary to hypoxia enhances fibrosis, RT worsens it. Oral squamous cell carcinoma occurring in the background of OSF is an absolute contraindication for RT as it augurs unfavorable prognosis. An algorithm to demonstrate this with evidence is clearly depicted. The role of HIF-1α in the progression of OSF and its malignant transformation, and the consideration of hyperbaric oxygen therapy as a therapeutic remedy in OSF are underscored.

Novel Candidate Biomarkers of Chemoradiosensitivity in Esophageal Squamous Cell Carcinoma: A Systematic Review

There is no doubt that, along with surgery, chemoradiotherapy is an important treatment for esophageal squamous cell carcinoma (ESCC). Patients who respond well to chemoradiotherapy obtain great benefits toward overcoming their cancer, and so a more favorable prognosis. On the other hand, patients who do not respond well have wasted valuable time and experienced severe toxicity and seriously diminished quality of life, only to have their cancer recur with an unfavorable prognosis. For this reason, a reliable biomarker of chemoradiosensitivity in ESCC has long been sought. In this review, we will enumerate recently reported candidate biomarkers of chemoradiosensitivity in ESCC that have the potential for future clinical application.

Low Cardiac Output Leads Hepatic Fibrosis in Right Heart Failure Model Rats

Background

Hepatic fibrosis progresses with right heart failure, and becomes cardiac cirrhosis in a severe case. Although its causal factor still remains unclear. Here we evaluated the progression of hepatic fibrosis using a pulmonary artery banding (PAB)-induced right heart failure model and investigated whether cardiac output (CO) is responsible for the progression of hepatic fibrosis.

Methods and Results

Five-week-old Sprague-Dawley rats divided into the PAB and sham-operated control groups. After 4 weeks from operation, we measured CO by echocardiography, and hepatic fibrosis ratio by pathological examination using a color analyzer. In the PAB group, CO was significantly lower by 48% than that in the control group (78.2±27.6 and 150.1±31.2 ml/min, P<0.01). Hepatic fibrosis ratio and serum hyaluronic acid, an index of hepatic fibrosis, were significantly increased in the PAB group than those in the control group (7.8±1.7 and 1.0±0.2%, P<0.01, 76.2±27.5 and 32.7±7.5 ng/ml, P<0.01). Notably, the degree of hepatic fibrosis significantly correlated a decrease in CO. Immunohistological analysis revealed that hepatic stellate cells were markedly activated in hypoxic areas, and HIF-1α positive hepatic cells were increased in the PAB group. Furthermore, by real-time PCR analyses, transcripts of profibrotic and fibrotic factors (TGF-β1, CTGF, procollargen I, procollargen III, MMP 2, MMP 9, TIMP 1, TIMP 2) were significantly increased in the PAB group. In addition, western blot analyses revealed that the protein level of HIF-1α was significantly increased in the PAB group than that in the control group (2.31±0.84 and 1.0±0.18 arbitrary units, P<0.05).

Conclusions

Our study demonstrated that low CO and tissue hypoxia were responsible for hepatic fibrosis in right failure heart model rats.

Epigenetic Mechanisms of the Aging Human Retina

Degenerative retinal diseases, such as glaucoma, age-related macular degeneration, and diabetic retinopathy, have complex etiologies with environmental, genetic, and epigenetic contributions to disease pathology. Much effort has gone into elucidating both the genetic and the environmental risk factors for these retinal diseases. However, little is known about how these genetic and environmental risk factors bring about molecular changes that lead to pathology. Epigenetic mechanisms have received extensive attention of late for their promise of bridging the gap between environmental exposures and disease development via their influence on gene expression. Recent studies have identified epigenetic changes that associate with the incidence and/or progression of each of these retinal diseases. Therefore, these epigenetic modifications may be involved in the underlying pathological mechanisms leading to blindness. Further genome-wide epigenetic studies that incorporate well-characterized tissue samples, consider challenges similar to those relevant to gene expression studies, and combine the genome-wide epigenetic data with genome-wide genetic and expression data to identify additional potentially causative agents of disease are needed. Such studies will allow researchers to create much-needed therapeutics to prevent and/or intervene in disease progression. Improved therapeutics will greatly enhance the quality of life and reduce the burden of disease management for millions of patients living with these potentially blinding conditions.

Placental growth factor inhibition modulates the interplay between hypoxia and unfolded protein response in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality. We previously showed that the inhibition of placental growth factor (PlGF) exerts antitumour effects and induces vessel normalisation, possibly reducing hypoxia. However, the exact mechanism underlying these effects remains unclear. Because hypoxia and endoplasmic reticulum stress, which activates the unfolded protein response (UPR), have been implicated in HCC progression, we assessed the interactions between PlGF and these microenvironmental stresses.

Methods

PlGF knockout mice and validated monoclonal anti-PlGF antibodies were used in a diethylnitrosamine-induced mouse model for HCC. We examined the interactions among hypoxia, UPR activation and PlGF induction in HCC cells.

Results

Both the genetic and pharmacological inhibitions of PlGF reduced the chaperone levels and the activation of the PKR-like endoplasmic reticulum kinase (PERK) pathway of the UPR in diethylnitrosamine-induced HCC. Furthermore, we identified that tumour hypoxia was attenuated, as shown by reduced pimonidazole binding. Interestingly, hypoxic exposure markedly activated the PERK pathway in HCC cells in vitro, suggesting that PlGF inhibition may diminish PERK activation by improving oxygen delivery. We also found that PlGF expression is upregulated by different chemical UPR inducers via activation of the inositol-requiring enzyme 1 pathway in HCC cells.

Conclusions

PlGF inhibition attenuates PERK activation, likely by tempering hypoxia in HCC via vessel normalisation. The UPR, in turn, is able to regulate PlGF expression, suggesting the existence of a feedback mechanism for hypoxia-mediated UPR that promotes the expression of the angiogenic factor PlGF. These findings have important implications for our understanding of the effect of therapies normalising tumour vasculature.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1990-6) contains supplementary material, which is available to authorized users.

Viability, function and morphological integrity of precision-cut liver slices during prolonged incubation: Effects of culture medium

Precision-cut liver slices (PCLS) are an ex vivo model for metabolism and toxicity studies. However, data on the maintenance of the morphological integrity of the various cell types in the slices during prolonged incubation are lacking. Therefore, our aims were to characterize morphological and functional changes in rat PCLS during five days of incubation in a rich medium, RegeneMed®, and a standard medium, Williams' Medium E. Although cells of all types in the slices remain viable, profound changes in morphology were observed, which were more prominent in RegeneMed®. Slices underwent notable fibrosis, bile duct proliferation and fat deposition. Slice thickness increased, resulting in necrotic areas, while slice diameter decreased, possibly indicating cell migration. An increased proliferation of parenchymal and non-parenchymal cells (NPCs) was observed. Glycogen, albumin and Cyp3a1 were maintained albeit to a different level in two media. In conclusion, both hepatocytes and NPCs remain viable and functional, enabling five-day toxicity studies. Tissue remodeling and formation of a new capsule-like cell lining around the slices are evident after 3–4 days. The differences in effects between media emphasize the importance of media selection and of the recognition of morphological changes in PCLS, when interpreting results from toxicological or pharmacological studies.

RETRACTED: Effects of geniposide on hepatocytes undergoing epithelial-mesenchymal transition in hepatic fibrosis by targeting TGFβ/Smad and ERK-MAPK signaling pathways

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. The corresponding author, Dr Byoungduck Park, requested publication of a corrigendum to correct figure 2B which reused control data from a different publication (doi: 10.1016/j.intimp.2015.02.014). Upon further inspection, the Biochimie editorial team noticed that: Comparison of Fig 2B with Fig 4C of a previous publication in International Immunopharmacology by two co-authors (doi: 10.1016/j.intimp.2015.02.014) reveals that western blot β-actin control data from the earlier paper were re-used in a different experiment shown in Figure 2B of the article in Biochimie, after adjustment of the brightness/contrast. Furthermore, the same bands, after more image manipulation were presented as Smad3 data in Figure 4C of the Biochimie article. Here the image manipulation involved notably the rotation of the set of bands by 180° and some adjustment of the height/width ratio. The authors apologise for any confusion that may have arisen from their article.